Three of the dead were children. An additional 20 people were wounded by the blast in Kashmor district, which caused several train cars to run off the track, said police official Mohammad Azeem.

Kashmor is in Sindh province but adjoins Baluchistan. One of several ethnic Baluch separatist groups operating in the province, the Baluch Republican Army, claimed responsibility.

The groupís spokesman, Sarbaz Baluch, said in a phone call from an undisclosed location that the attack was a reaction to what he alleged were killings in Baluchistanís Dera Bugti region by Pakistani paramilitaries.

The group also blew up three gas pipelines last week, suspending supplies to millions of households for two days.